IM Distortion, Speakers and the Death of Science


One topic that often comes up is perception vs. measurements.

"If you can't measure it with common, existing measurements it isn't real."

This idea is and always will be flawed. Mind you, maybe what you perceive is not worth $1, but this is not how science works. I'm reminded of how many doctors and scientists fought against modernizing polio interventions, and how only recently did the treatment for stomach ulcers change radically due to the curiosity of a pair of forensic scientists.

Perception precedes measurement.  In between perception and measurement is (always) transference to visual data.  Lets take an example.

You are working on phone technology shortly after Bell invents the telephone. You hear one type of transducer sounds better than another.  Why is that?  Well, you have to figure out some way to see it (literally), via a scope, a charting pen, something that tells you in an objective way why they are different, that allows you to set a standard or goal and move towards it.

This person probably did not set out to measure all possible things. Maybe the first thing they decide to measure is distortion, or perhaps frequency response. After visualizing the raw data the scientist then has to decide what the units are, and how to express differences. Lets say it is distortion. In theory, there could have been a lot of different ways to measure distortion.  Such as Vrms - Vrms (expected) /Hz. Depending on the engineer's need at the time, that might have been a perfectly valid way to measure the output.

But here's the issue. This may work for this engineer solving this time, and we may even add it to the cannon of common measurements, but we are by no means done.

So, when exactly are we done?? At 1? 2? 5?  30?  The answer is we are not.  There are several common measurements for speakers for instance which I believe should be done more by reviewers:

- Compression
- Intermodulation ( IM ) Distortion
- Distortion

and yet, we do not. IM distortion is kind of interesting because I had heard about it before from M&K's literature, but it reappeared for me in the blog of Roger Russel ( http://www.roger-russell.com ) formerly from McIntosh. I can't find the blog post, but apparently they used IM distortion measurements to compare the audibility of woofer changes quite successfully.

Here's a great example of a new measurement being used and attributed to a sonic characteristic. Imagine the before and after.  Before using IM, maybe only distortion would have been used. They were of course measuring impedance and frequency response, and simple harmonic distortion, but Roger and his partner could hear something different not expressed in these measurements, so, they invent the use of it here. That invention is, in my mind, actual audio science.

The opposite of science would have been to say "frequency, impedance, and distortion" are the 3 characteristics which are audible, forever. Nelson pass working with the distortion profile, comparing the audible results and saying "this is an important feature" is also science. He's throwing out the normal distortion ratings and creating a whole new set of target behavior based on his experiments.  Given the market acceptance of his very expensive products I'd say he's been damn good at this.

What is my point to all of this?  Measurements in the consumer literature have become complacent. We've become far too willing to accept the limits of measurements from the 1980's and fail to develop new standard ways of testing. As a result of this we have devolved into camps who say that 1980's measures are all we need, those who eschew measurements and very little being done to show us new ways of looking at complex behaviors. Some areas where I believe measurements should be improved:

  • The effects of vibration on ss equipment
  • Capacitor technology
  • Interaction of linear amps with cables and speaker impedance.

We have become far too happy with this stale condition, and, for the consumers, science is dead.
erik_squires
He can say it. That does not make it remotely correct:
Ok now I understand what you want to say and what is your conception very clearly.... Thanks....


Do you know why he said that? Not the mathematical or physical, biological argument, but the spiritual insight that guide him?
heaudio123
What matters is that all those smarts of the brain and their ability to pull information out of a sound (and visual ) field is completely meaningless wrt defining what happens with an electrical signal. So called audiophiles without any real technical knowledge repeatedly try to use this false argument that the complexities of sound field interpretation somehow translate to equal complexities AND variables for electrical signal transmission and use that logical fallacy for their justification of all kinds of never measured, never characterized and certainly never validated effects and characteristics in electrical signal recording, transmission and playback.

>>>>At least it’s the ones without any technical knowledge who try to use that phoney baloney argument. Are you sure you’re not Ethan Winer? For real? 

So called audiophiles without any real technical knowledge repeatedly try to use this false argument that the complexities of sound field interpretation somehow translate to equal complexities AND variables for electrical signal transmission and use that logical fallacy for their justification of all kinds of never measured, never characterized and certainly never validated effects and characteristics in electrical signal recording, transmission and playback.
It is not an argument that the electrical audio signal is conveyed trough an electrical grid of a particular house, in the mechanical resonant constraints of a particular audio system, through a very specific acoustical field in a particular room to be recreated by the ears-brain in some individual qualitative experience, irreducible to our actual measuring process...It is a simple fact....But I think that the improved measuring process can improve this experience yes....


And you contest a great physician mathematician about something you dont understand it seems...And accuse us "idiot" audiophiles ... :)


I smile because engineering for you is a bit distant of mathematics ( those of Penrose are not kitchen mathematics of 19 century) and philosophy it seems...Engineering is not only science , it is based on science, it is an art like medecine… There exist engineers that are also "idiot" audiophiles themselves and they work to create great audio....They dont buy the " fallacy" you speak about because all engineers are not scientist ideologue....They create for the human ears-brain, for the idiot audiophile to buy their products...

 I know what your work or hobby is for sure: it is measuring.... Nothing against that at all... It is very good and necessary thing to  do for improving  Audio for sure.... But remember:  «for a hammer all is nails»


Ha ha ha, "science is dead", what a joke!  Science can show you the transfer function between the source and the end result in the air at your place!
Sure it can't measure your tastes and the way your ears translate the air movement to your brain!
All we want to achieve is, within many constraints, the nearest end reproduction of the original sound taken from the source instruments / voice.

So don't bother with science, it's doing very well and isn't going anywhere!
Sure it can’t measure your tastes and the way your ears translate the air movement to your brain!
Very good point... We understand each other a little more...

It is just that there exist many other points that cannot be measured or that are not measured at this moment by scientist now in audio experience...One by one these points can be explained, many of them.... But when an audiophile create his room he plays with some basic science, and also with other factors to improve the sound...These factors are not always only the regular one studied by engineers that’s all... They exist.... I play with them with great success....My very real " illusion" of sound comes from them not only from good design electronic components....

If someone negate science I will not complaint if you call him an idiot, but negating some experience not directly linked to usual engineer experiment and calling audiophiles idiot is not good diplomacy....


By the way I am sure the OP was not speaking of the death of science " per se" but the narrow vision of some in audio science....Is it not clear? Or do you feel better in classifying anybody that is not engineer in idiot crowds?